Cannot build: "project not supported"

I have an outdated project (Reproducible Data Science | Open Research | Renku), which I have not been able to migrate to the new renku locally, as I was not able to upgrade my renku (see my other post). Then I tried to start the environment on renkulab and migrate it there, but I keep getting the following error message: “Error: This project is not supported”. Is this due to the outdated project? I wish it would still be possible to run outdated projects online and upgrade them there, otherwise the possibility to share and collaborate on projects online is very short-lived. Why can’t the renku version be recorded and saved along with the project, so that docker would be able to re-create a functioning environment?

I think I figured it out. For some reason if the project on the main branch is outdated, updating it another branch will still not allow building a new environment based on that branch, I kept getting the error message that the project is not supported. Only after merging the migrated project into main was I able to build a new environment on renkulab.